“When the Strong Outbreed the Weak” ↦

An experiment in selective breeding for a desirable trait shows that the simple approach does not produce the expected outcome:

The purpose of the experiment was to increase the egg-laying productivity of hens. The hens were housed in cages with nine hens per cage. Very simply, the most productive hen from each cage was selected to breed the next generation of hens.

If egg-laying productivity is a heritable trait, then the experiment should produce a strain of better egg layers, but that’s not what happened. Instead, the experiment produced a strain of hyper-aggressive hens[…]. There are only three hens [left in the final cage] because the other six were murdered and the survivors have plucked each other in their incessant attacks. Egg productivity plummeted, even though the best egg-layers had been selected each and every generation.

The reason for this perverse outcome is easy to understand, at least in retrospect. The most productive hen in each cage was the biggest bully, who achieved her productivity by suppressing the productivity of the other hens. Bullying behavior is a heritable trait, and several generations were sufficient to produce a strain of psychopaths.

There are many, many interesting things to learn here. Most directly, this is a lesson in just how complex biology is. But there may also be lessons here for human society:

In a parallel experiment, Muir monitored the productivity of the cages and selected all of the hens from the best cages to breed the next generation of hens. […] Egg productivity increased 160% in only a few generations, an almost unheard of response to artificial selection in animal breeding experiments.

It’s easy to credit the director with the success of a great movie. But have have you ever watched the entire list of credits at the end of your favorite movie? Modern movies do not spring, fully formed, out of the mind of the director, as Athena from Zeus. Nor are they simple collaborations among the director and actors. They are the products of small armies of people, working collectively to produce something far greater than any one of them could achieve on his or her own. The same is true of any great achievement.